Dynamic route branching system and dynamic route branching method

ABSTRACT

A system that includes a plurality of nodes to forward a data packet in a network, includes a controller to select at least a node dividing a data path of the data packet into a first path and a second path, from the nodes, based on a condition of the data path, and a node selected by the controller being capable of forwarding the packet to the first path and the second path according to an instruction from the controller. The second path includes a bypass path of the first path.

The present application is a Continuation application of U.S. patentapplication Ser. No. 13/510,622, filed on May 17, 2012, which is basedon International Application No. PCT/JP2010/070208, filed on Nov. 12,2010, which is based on and claims priority from Japanese patentapplication No. 2009-263342, filed on Nov. 18, 2009, the entire contentsof which are incorporated herein by reference.

TECHNICAL FIELD

The present invention is related to a dynamic route branching system,and especially, to a dynamic route branching system in a network whichadopts a multipath route communication.

BACKGROUND ART

Conventionally, there were the following problems (1)-(3) in case ofmultipath route communication to improve the communication when thetraffic is discarded in a network due to an insufficient link band widthon a route in the network.

(1) It was difficult to dynamically adopt a multipath route according tothe reception situation of the traffic of each terminal.

(2) When adopting the multipath route, it was difficult to select anidentical copy (full mirroring) and a partial copy (partial mirroring),a flow base division, a random division and so on in a split positionaccording to the situation of the network.

(3) It was difficult to adopt the dynamic optimum design so as tominimize the cost imposed on the network by taking a multipath route.

Regarding the problem (1), as a generally used multipath routegeneration technique, there are “OSPF ECMP technique” (Open ShortestPath First Equal Cost Multi Path), “MPLS Traffic Engineering technique”(Multi Protocol Label Switching Traffic Engineering) and so on.

In “the OSPF ECMP technique”, because a multipath route is staticallygenerated according to network topology and a link cost in the network,a plurality of routes are generated in a portion of the multipath routeof the identical cost in the network. However, it is difficult to set aplurality of routes in an optional position, and the route is selectedin a flow base by the Hash function in the split position of themultipath. Therefore, it is difficult to control according to thereception situation of the traffic of each terminal.

On the other hand, in “MPLS Traffic Engineering technique”, a multipathroute is dynamically generated according to the network topology, thelink cost, and a traffic amount flowing through the link. However, themultipath can not be generated from a node on the way of the network andit is difficult to control according to the reception situation of thetraffic of each terminal.

Therefore, it is demanded that multipath route is dynamically generatedaccording to the reception situation of the traffic flow of eachterminal to improve the traffic reception performance of the terminal.

Regarding the problem (2), a plurality of routes are prepared previouslyat the edge of the network, as shown in JP 2004-312153A (PatentLiterature 1), and JP 2007-94681 A (Patent Literature 2). It should benoted that the edge of the network is an entrance of the network.

In JP 2004-312153 A (Patent Literature 1), a method is disclosed inwhich in the environment that optical edges are connected to both of anIP network (Internet Protocol Network) and a photonic network, tworoutes are set previously, and communication is switched to the side ofthe photonic network when the a predetermined quantity of traffic flowsthrough the IP network. In this method, communication is switched to thephotonic network when detecting a large amount of traffic, becauseenough performance can not be attained in a large capacity communicationof the IP network. In this way, because this method carries out a simpleswitching control between the networks, a function of branching in anoptional position in the network and copy and division functions such asthe identical copy, the partial copy, the flow base division and therandom division can not be attained.

On the other hand, in JP 2007-94681A (Patent Literature 2), a method isdisclosed in which a redundant route candidacy (a route which is notallocated with a resource) is provided previously when a plurality ofroutes in the network are provided, and a resource is allocated oncemore at a necessary time. In this method, the redundant path is notallocated with a resource previously, and a plurality of transmissionservers shares a route. In this way, because this method is related to aresource sharing method of a redundant path, a function of branching inan optional position of the network and the functions such as theidentical copy, the partial copy, the flow base division and the randomdivision can not be attained.

Moreover, in the problem (2), as shown in JP 2007-208953A (PatentLiterature 3), a technique is known in which a plurality of multicastpaths are dynamically set in the edge of the network (entrance of thenetwork). In JP 2007-208953A (Patent Literature 3), a method ofgenerating a plurality of multicast trees is disclosed. This method usesa hash function in use after the generation. However, a destination forthe traffic to be transferred to according to the contents and a routebranched from a transmission source (edge) of the multicast aredetermined by use of the hash function that regarding the route of themulticast. In this way, because this method is to make the multicasttree itself redundant, there is no function of branching in an optionalposition in the network and of a copy and division such as an identicalcopy, a partial copy, a flow base division and a random division.

Therefore, when adopting the multipath route, a technique is demanded inwhich either of the identical copy, the partial copy, the flow basedivision, the random division and so on is dynamically selected in thesplit position according to the situation of the network, so as toimprove in the traffic reception performance of the terminal.

Regarding the problem (3), because a load is imposed on the network dueto the traffic subjected to the multicast communication when themulticast communication is branched from an optional route, it isrequired to maximize the reception performance of the terminal whilesuppressing the load as much as possible. However, as mentioned above,because there is not a function of branching in the optional position inthe network in a conventional method, there is no technique formaximizing reception performance of the terminal.

CITATION LIST

-   [Patent Literature 1] JP 2004-312153A-   [Patent Literature 2] JP 2007-94681A-   [Patent Literature 3] JP 2007-208953A

[Non-Patent Literature 1]

-   “The OpenFlow The switch Consortium” <http: //www.openflowthe    switch.org/>

[Non-Patent Literature 2]

-   “OpenFlow The switch Specification Version 1.0.0 (Wire Protocol    0x01) Dec. 31, 2009”<http://www.openflowthe    switch.org/documents/openflow-spec-v1.0.0.pdf>

SUMMARY OF THE INVENTION

In the present invention, a branching method such as a copy and adivision, and a split route are calculated, and the traffic flow isdynamically branched to a plurality of routes by the branching methodsuch as the copy and the division in positions of one or more optionalnodes of the nodes through which the communication traffic passes, torestore the traffic on the reception side, in order to attemptoptimization based on the maximization and stabilization of thereception quality by monitoring the reception quality of communicationtraffic flow on a network, a split position of the traffic.

A dynamic route branch system of the present invention is provided witha managing unit and a dynamic route branching unit. The control unitmonitors reception quality of a traffic on a network and carries outdynamic route setting to an optional node in the network. The dynamicroute branching unit is possibly arranged in a reception terminal as adestination of the traffic. The dynamic route branching unit is providedin the node and includes at least one of: a monitoring sectionconfigured to monitor the traffic flow having reached the node whenbeing provided in the node in the network, and to notify the monitoringresult to the control unit; a splitting section configured to split thetraffic flow received from a node at a previous stage to the node intosplit traffic flows which are transmitted onto an initial route and asplit route in response to an instruction from the control unit, whenbeing provided in the node relaying the traffic flow in the network; anda merging section configured to merge the split traffic flows havingreached through the initial route and the split route to restore thetraffic flow when being provided in a node at a subsequent stage to thenode. It should be noted that network the network may be a wire networkor a wireless network. As an example of a node on the network, a switchis assumed. Here, the monitoring section and the merging section mayexist on the reception terminal and the managing unit.

A dynamic route branching unit of the present invention which ispossibly provided in a node relaying a traffic flow on a network and areception terminal as a destination of the traffic flow, includes: amonitoring section configured to monitor the traffic flow having reachedthe node when being provided in the node in the network, and to notifythe monitoring result to the control unit; a splitting sectionconfigured to split the traffic flow received from a node at a previousstage to the node into split traffic flows which are transmitted onto aninitial route and a split route in response to an instruction from thecontrol unit, when being provided in the node relaying the traffic flowin the network; and a merging section configured to merge the splittraffic flows having reached through the initial route and the splitroute to restore the traffic flow when being provided in a node at asubsequent stage to the node.

In a dynamic route branching method, a control unit monitors receptionquality of a traffic flow on a network to carry out dynamic routesetting to an optional node on the network. Also, it monitors a trafficflow having reached a predetermined node on the network to notify amonitoring result to the control unit. A node splits and transmits thetraffic flow received from a split node at a previous stage to a noderelaying the traffic flow on the network onto an initial route and asplit route in response to an instruction from the control unit. A nodeof a subsequent stage to the splitting node merges the traffic flowshaving reached through the initial route and the split route to restorethe traffic flow in a node at a subsequent stage to the split node.

A program of the present invention is executed by a computercorresponding to at least one out of the node which relays traffic onthe network and the reception terminal which is the address of thetraffic. The computer which executes this program is possible to monitortraffic and to notify the monitoring result to the managing unit whichcarries out a dynamic route setting to an optional node on the network.Also, it is possible to branch and transmit the traffic to an initialroute and a split route in response to an instruction from the managingunit. Also, it is possible to merge the traffics having reached throughthe initial route and the split route to restore. It should be notedthat the program of the present invention can be stored in the storageand the storage medium.

Even if a phenomenon that a traffic flow is discarded in a main routedue to the change of state in the network occurs, the whole traffic isquickly restored by using the traffic on the sub-route, so as to improvethe traffic reception performance of the reception terminal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing a basic configuration example of adynamic route branching system of the present invention;

FIG. 2 is a diagram showing a first exemplary embodiment of the presentinvention;

FIG. 3 is a diagram showing a splitting method;

FIG. 4 is a diagram showing a merging method;

FIG. 5 is a diagram showing a second exemplary embodiment of the presentinvention;

FIG. 6 is a diagram showing a third exemplary embodiment of the presentinvention;

FIG. 7 is a diagram showing a fourth exemplary embodiment of the presentinvention;

FIG. 8 is a diagram showing a fifth exemplary embodiment of the presentinvention;

FIG. 9 is a diagram showing a sixth exemplary embodiment of the presentinvention;

FIG. 10 is a diagram showing a seventh exemplary embodiment of thepresent invention;

FIG. 11 is a diagram showing an eighth exemplary embodiment of thepresent invention; and

FIG. 12 is a diagram showing a ninth exemplary embodiment of the presentinvention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Basic Configuration

Hereinafter, the basic configuration of the present invention will bedescribed with reference to the attached drawings.

As shown in FIG. 1, the dynamic route branching system of the presentinvention is provided with a transmission terminal 10, switches 20(20-i, i=1 to n: n is the number of switches), a network control unit 30and a reception terminal 40.

The transmission terminal 10 transmits packets of character data, speechdata, video data and so on to the reception terminal 40 through any ofthe switches 20 (20-i, i=1 to n) corresponding to nodes on the network.A data amount of the packets transmitted on the network is called atraffic (flow). The network control unit 30 is a management unit whichmonitors the reception quality of the traffic (flow) on the network andcarries out a dynamic route setting to the switches 20 (20-i, i=1 to n).In this case, the network control unit 30 is communicable with each ofthe switches 20 (20-i, i=1 to n), and manages topology data (networktopology), the band width data of a network link and so on of the wholenetwork, and carries out the optimum design of a branch or splitposition (a switch at a split start point) and a branch or split route.

Each of the switches 20 (20-i, i=1 to n) is provided with a dynamicroute branching unit 50. That is, the dynamic route branching units 50of the same number as the switches 20 exist. It should be noted thatactually, the dynamic route branching unit 50 may be the switches 20itself.

The dynamic route branching unit 50 is provided with a monitoringsection 51, a splitting section 52 and a merging section 53. Therefore,each of the switches 20 (20-i, i=1 to n) is provided with the monitoringsection 51, the splitting section 52 and the merging section 53.However, each of the switches 20 (20-i, i=1 to n) is not necessary tocontain all of the monitoring section 51, the splitting section 52 andthe merging section 53, and is sufficient to contain any of themonitoring section 51, the splitting section 52 and the merging section53 to be used at least.

The monitoring section 51 monitors received packets and notifies themonitoring result to the network control unit 30.

The splitting section 52 transmits the received packet on a routeselected by the network control unit 30. At this time, the splittingsection 52 splits the received packets, if necessary, and distributesand transmits each of the branched packets onto the route selected bythe network control unit 30.

The merging section 53 merges split traffics to restore an appropriatetraffic. At this time, if the received packet is the split packet, themerging section 53 outputs a packet flow obtained by merging splitpacket, and if the received packet is not the split packet, the mergingsection 53 outputs it just as it is.

The network control unit 30 attempts minimization of resources used in aroute to a destination of the multipath and maximization/stabilizationof reception quality in the destination based on a split positionselection algorithm. Specifically, the network control unit 30 selects aroute in which a total of the resource use amounts over the whole routeis minimum or a route in which the stability of the network is high, ofthe routes in which performance is maximized after merging the splitpackets. As an example of the resource use amount, calculation result of“Hop number×band width”, a calculation result of “distance×band width”and so on are exemplified. However, actually, it is not limited to theseexamples. It should be noted that Hop number is the number of switchesthrough which the packet passes from the transmission terminal 10 to thereception terminal 40.

(Example of Hardware)

It should be noted that as an example of the transmission terminal 10and the reception terminal 40, a PC (personal computer) and a mobilephone are exemplified. In addition, as an example of the transmissionterminal 10 and the reception terminal 40, a thin client terminal, awork station, a mainframe, a supercomputer, a car navigation system, acarrying game machine, a home game machine, a gadget (electronicequipment), an interactive TV, a digital tuner, a digital recorder, aninformation home appliance, a POS (Point of Sale) terminal, an OA(Office Automation) equipment, and so on are exemplified. Also, as anexample of the network control unit 30, a computer such as a PC, a thinclient server, a work station, a mainframe, and a supercomputer areexemplified. The transmission terminal 10, the network control unit 30,and the reception terminal 40 may be mounted on mobile bodies such as avehicle, a ship, and an aircraft.

Also, as an example of the switches 20 (20-i, i=1 to n), a layer 2switch which relays data on a data link layer (the second layer), alayer 3 switch which relays data on a network layer (the third layer), alayer 4 switch which relays data on a transport layer (the fourthlayer), a layer 7 switch (an application switch) which relays data on anapplication layer (the seventh layer), a multi-layer switch (multi-layerswitch) and so on are exemplified. The multi-layer switch is classifiedin detail every layer of the OSI Reference Model. Besides, as an exampleof the switches 20 (20-i, i=1 to n), a proxy server, a gateway, afirewall, a load balancer (a load distribution apparatus), a computerand a relay equipment which are equivalent to them and so on areexemplified.

Moreover, as an example of the network on which the switches 20 (20-i,i=1 to n) exist, the Internet, a LAN (Local Area Network), a wirelessLAN, a WAN (Wide Area Network), a backbone, a community antennatelevision system (CATV) line, a fixation telephone network, a mobilephone network, a WiMAX (IEEE 802.16a), 3G (3rd Generation), a leaseline, IrDA (Infrared Data Association), Bluetooth (registeredtrademark), a serial communication line, a data bus and so on areexemplified.

Each of the monitoring section 51, each of the splitting section 52 andthe merging section 53 is realized by an electronic circuitcorresponding to the function. Or, each of the monitoring section 51,the splitting section 52 and the merging section 53 may be realized by ahardware configuration such as a processor driven based on a program, asoftware configuration such as a program to drive the hardwareconfiguration so as to perform desired processing, and a storage unitwhich stores the software and data of various kinds.

As an example of the above-mentioned processor, a CPU (CentralProcessing Unit), a microprocessor, a microcontroller, a semiconductorintegrated circuit (IC) which has a similar function and so on areexemplified. However, actually, it is not limited to these examples.

Also, as an example of the above-mentioned storage unit, semiconductormemory devices such as RAM (Random Access Memory), ROM (Read OnlyMemory), EEPROM (Electrically Erasable and Programmable Read OnlyMemory) and a flash memory, secondary storage units such as a HDD (HardDisk Drive) and an SSD (Solid State Drive), storage media such as DVD(Digital Versatile Disk) and a memory card are exemplified.

However, actually, it is not limited to these examples.

First Exemplary Embodiment

Next, the first exemplary embodiment of the present invention will bedescribed.

In the present exemplary embodiment, as shown in FIG. 2, a case in whicha monitoring process is executed only in the switch (Egress switch) 20at the last stage which is the nearest to the reception terminal 40, ofthe switches 20 (20-i, i=1 to n) in the network will be described. Inthe present exemplary embodiment, the monitoring section 51 and themerging section 53 are provided in the switch (Egress switch) 20 at thelast stage, and the splitting section 52 is provided in optionalswitches 20. That is, the monitoring section 51 and the merging section53 function only in the switch (Egress switch) 20 at the last stage, andthe splitting section 52 functions in all the switches of the network.

In an example of FIG. 2, the monitoring section 51 monitors the networkquality of the traffic which is transmitted on an initial route from thetransmission terminal 10 to the reception terminal 40, in the switch(Egress switch) 20 at the last stage which is the nearest to thereception terminal 40. The splitting section 52 splits a traffic flow ina relay switch. The merging section 53 merges split traffic flows torestore an appropriate traffic flow and then transmits it to thereception terminal 40. The network control unit 30 grasps topology dataof the whole network, the band width data of the network link and so on,and carries out the optimum design of a split position and a splitroute.

Regarding a specific operation, the monitoring section 51 monitors thetraffic flow which is transmitted on the initial route from thetransmission terminal 10 to the reception terminal 40 at the switch(Egress switch) 20 at the last stage in response to an instruction fromthe network control unit 30. The monitoring section 51 notifies asituation analysis of the network and an alarm (warning) to the networkcontrol unit 30 when a network loss, a delay deviation, and degradationof the throughput are monitored in this traffic flow.

The network control unit 30 dynamically grasps the topology data of thenetwork, the band width data of the network link and a change of theband width data, and determines each of a flow splitting method, acoding method, a split position, a split route according to the abovealarm.

(Splitting Method)

Regarding the splitting method, the network control unit 30 can selectdifferent methods such as an identical copy (full mirroring), a partialcopy (partial mirroring), a flow based division and a random division.At this time, the network control unit 30 determines which of theidentical copy, the partial copy, the flow base division and the randomdivision should be selected as the splitting method in the entiretraffic flow or every traffic flow, and sets the selected splittingmethod to the splitting section 52. It should be noted that the networkcontrol unit 30 may set the splitting method to the splitting section 52in response to an inquiry from the splitting section 52 which receivedthe packet. Also, when the splitting section 52 refers to the data ofthe splitting method stored in the network control unit 30 voluntarily(periodically/according to a condition) and performs the processing, thesame is essentially similar.

(Description of Cases) “The identical copy (model A)”, “the partial copy(model B)”, “the flow base division and the random division (model C)”are shown in FIG. 3 as examples of the splitting method.

(Case 1)

First, a case of “the identical copy (model A)/the partial copy (modelB)” will be described.

For example, when the load is high as the whole network and a loss inthe network occurs in any route, or when the network is unstable so asto require a long time for restoration in case of a fault occurrence inthe network, the network control unit 30 instructs the splitting section52 to execute the identical copy (model A) or the partial copy (modelB).

(Identical Copy)

In case of the identical copy, the splitting section 52 copies theentire traffic flow unconditionally and transmits them by a plurality ofroutes such as the initial route and a detour route (a split route). Inthe switch (egress switch) 20 at the last stage on the side of thereception terminal 40, the merging section 53 discards an overlappingportion from the traffic flows transmitted through the plurality ofroutes such as the initial route and the detour route to restore theright traffic flow, and transmits the right traffic flow to thereception terminal 40. Or, the merging section 53 transmits only theright traffic flow having reached through either of the plurality ofroutes such as the initial route and the detour route, to the receptionterminal 40. In this case, even if a loss and an error occur in thetraffic flow having reached through the initial route, the high-speedswitching is possible for a network fault, because the right trafficflow can be restored based on the copied traffic flow having reachedthrough any detour route.

(Partial Copy)

In case of the partial copy, the splitting section 52 carries out amirroring partially to the received traffic flow, transmits the receivedtraffic flow onto the initial route, and at the same time, transmits thecopied traffic flow on the detour route. In this case, the splittingsection 52 extracts a traffic flow with a high priority (a traffic flowwith predetermined data showing the high priority, a traffic flow with apriority higher than a predetermined value) of the received trafficflows, and copies and transmits the copied traffic flow with the highpriority onto the plurality of routes. Also, the splitting section 52transmits the received traffic flow just as it is, on the initial routewithout carrying out the mirroring to the traffic flow with a prioritywhich is not so high.

As an example of the traffic flow with the high priority, a traffic flowof data of a specific kind, a traffic flow showing a specifictransmission source/transmission destination and so on are exemplified.However, the priority is only an example. Actually, it may be determinedwhether or not the partial copy is permitted based on a condition exceptthe priority.

By carrying out the mirroring only to the traffic flow with the highpriority, the increase of the traffic flow can be restrained, comparedwith a case where the identical copy is carried out to all the trafficflows. In the switch (Egress switch) 20 at the last stage on the side ofthe reception terminal 40, the merging section 53 restores the righttraffic flow by discarding an overlapping portion from each of thetraffic flows with the high priority having reached through theplurality of routes such as the initial route and the detour route andtransmits the restored right traffic to the reception terminal 40. Or,the merging section 53 transmits only the right traffic flow from thetraffic flows with the high priority having reached through either ofthe plurality of routes such as the initial route and the detour routeto the reception terminal 40. Also, the merging section 53 transmits thetraffic flows having reached through the routes to the receptionterminal 40 just as it is, if the traffic flows have priorities whichare not so high. In this case, even if a loss and an error occur in onlythe traffic flows with the high priority having reached on the initialroute, the high-speed switching becomes possible to the network fault,because the right traffic flow can be restored based on the copiedtraffic flow having reached through any detour route.

(Case 2)

Next, a case of “flow base division/random division (model C)” will bedescribed.

For example, when few bands exist on the whole network in a trafficsystem in which the loss in the whole network does not cause a problem,the network control unit 30 instructs the splitting section 52 toexecute the flow base division (model C) or the random division (modelC).

(Flow Base Division)

In case of the flow base division, the splitting section 52 changes theroute every flow group based on flow data. In the switch (Egress switch)20 at the last stage on the side of the reception terminal 40, themerging section 53 receives all the flow groups and transmits to thereception terminal 40.

(Random Division)

In case of the random division, the splitting section 52 changes theroute randomly every packet. For example, the splitting section 52alternately/randomly distributes the received packets to two splitroutes and transmits them. The same thing is applied in case of two ormore split routes.

In the switch (Egress switch) 20 at the last stage on the side of thereception terminal 40, the merging section 53 receives all the packetsand transmits them to the reception terminal 40. However, in case of therandom division, it is necessary that a buffer is provided for theswitch (Egress switch) 20 itself at the last stage on the side of thereception terminal 40 or the merging section 53 to accumulate thereceived packets, the merging section 53 in the switch (Egress switch)20 at the last stage on the side of the reception terminal 40 transmitsthe packets after the reassembling of the packets (packet reordering).

(Combination of Splitting Methods (Composite))

It should be noted that “the identical copy (model A)”, “the partialcopy (model B)”, “the flow base division and the random division (modelC)” can be combined and executed. For example, when adopting “theidentical copy (model A)/the partial copy (model B)”, it is thought ofto further adopt “the flow base division and the random division (modelC)” to the copied traffic flow. Oppositely, when adopting “the flow basedivision and the random division (model C)”, it can be thought of tofurther adopt “the identical copy (model A)/the partial copy (model B)”to the divided traffic. However, actually, it is not limited to theseexamples.

(Coding Method)

There are the following two coding methods.

One is a method in which any special processing is not carried out asusual packet processing. In this case, especially, the coding is notcarried out. That is, the network control unit 30 sets nothing to thesplitting section 52. The splitting section 52 transmits all the trafficflows just as they are.

The other is a method in which the transmission terminal 10 or either ofthe network switches 20 (20-i, i=1 to n) carries out special processingin which the coding is performed to the usual traffic flows every policyand relayed into the network. In this case, the transmission terminal 10or either of the switches 20 (20-i, i=1 to n) in the network carries outthe coding to add a priority, by using a method which is strong to thepacket loss (which has packet loss tolerance) in an optional route suchas hierarchization coding and multi-rate coding. The splitting section52 transmits the traffic flows by taking the split redundancy of themirroring to the traffic flow with a high priority and by passingthrough only a specific route to the traffic flow with a priority whichis not so high.

For example, it is supposed that the transmission terminal 10 or eitherof the switches 20 (20-i, i=1 to n) in the network carries out the datacoding by both of the hierarchization coding and multi-rate coding, andthe data are divided into four data A, B, C, and D in order of higherpriority. At this time, the splitting section 52 transmits data withhigh priorities (e.g. data A and B) to the route on the side on whichthe situation of the network is stable, at the split position (the relayswitch 20) of the traffic flow. In the switch (Egress switch) 20 at thelast stage on the side of the reception terminal 40, the merging section53 carries out the redundant reception control and merges the trafficflows.

(Branch Position)

Regarding the split position, for example, in FIG. 2, the networkcontrol unit 30 calculates and determines a route with the leastperformance loss of the detour routes which split from any of thesplitting sections 52 (52-1, 52-2, 52-3) and reaches the switch (Egressswitch) 20 at the last stage.

For example, it is supposed that the route from the splitting section 52(52-1) to the switch (Egress switch) 20 at the last stage is “4 Hop”(the number of Hops=4), the route from the splitting section 52 (52-2)to the switch (Egress switch) 20 at the last stage is “3 Hop” (thenumber of Hops=3), and the same performance can be provided. As anevaluation reference, the network control unit 30 compares the numbersof Hops and adopts a split route 1 from the splitting section 52 (52-2),because an influence to the network can be minimized when the distanceof the detour route is shorter as much as possible.

On the other hand, when all the routes are in a condition that it iseasy for the packet loss to occur due to congestion or in the conditionthat the network is unstable so that a probability of a fault is high,the network control unit 30 adopts both of the split route 1 from thesplitting section 52 (52-2) and the split route 2 from the splittingsection 52 (52-1). The splitting section 52 transmits the traffic flowonto the adopted split route as well as the initial route. In the switch(Egress switch) 20 at the last stage on the side of the receptionterminal 40, the merging section 53 merges the traffic flows havingreached through three routes of the initial route, the split route 1,and the split route 2 to guarantee the performance. In this determiningmethod, the network control unit 30 may use other evaluation referencessuch as minimization of a total of resource use amounts (the Hopnumber×band width, the distance×band width) over all of the initialroute, the split route 1, and the split route 2 or maximization andstabilization of the quality of the reception terminal 40.

(Branch Route)

Regarding the split route, the network control unit 30 calculates whichswitch the detour route from the splitting section 52 (52-1, 52-2)passes through. The network control unit 30 grasps and sets a bandwidth, a delay, a distance of the detour route on the network in thisprocessing.

As described above, when determining a split position, a splittingmethod, and a split route, the network control unit 30 issues aninstruction to the switch 20 corresponding to the split position, toinstruct the splitting method to be adopted to the splitting sections 52(52-1, 52-2) and so on, and sets the split route 1, the split route 2and so on which detour from the splitting section 52. In this way, thesetting of the branch to the switch 20 and the splitting sections 52 iscentralized on the network control unit 30.

As this setting method, it is possible to use a transmission destinationaddress (destination IP address) based static routing method, an MPLSbased path routing method, a flow switching method using the Openflowtechnique and so on.

(Openflow Technique)

It should be noted that the Openflow (open flow) technique means atechnique in which a controller (the network control unit 30 in thisexample) sets a multi-layer configuration and a route data in units offlows (flow table) to a switch based on flow definition data (flow:rule+action) set to itself as a routing policy, and carries out arouting control and a node control. In the open flow technique, thecontroller monitors the switches in the network and dynamically sets adelivery route of a packet to the switches in the network according tothe situation of the network. Thus, the routing control function isseparated from the switches and the optimal routing and traffic controlbecome possible through the centralized control by the controller. Theswitch to which the open flow technique is applied deals withcommunication not in units of packets or frames like the conventionalswitch but as a flow of end to end (End to End).

The flow in the open flow technique is defined with any of a destinationaddress, a source address, a destination port number, and a source portnumber contained in a header field of a TCP/IP (Transmission ControlProtocol/Internet Protocol) packet, or various combinations of them andis distinguishable. It should be noted that it is supposed that theabove-mentioned address contains a MAC address (Media Access ControlAddress) and an IP address (Internet Protocol Address). Also, it issupposed that the above-mentioned port contains a logical port and aphysical port.

In case of a flow switching method which uses the open flow technique,for example, it is possible to set an explicit route every optionaltraffic flow group which is recognized in an optional header field inthe layers of layer 1 to layer 4.

The details of the open flow technique have been described in Non-PatentLiteratures 1 and 2.

(Merge Processing on the Side of Reception Terminal)

As shown in FIG. 4, in the switch (Egress switch) 20 at the last stageon the side of the reception terminal 40, the merging section 53receives the traffic flows which are centralized from a plurality ofsplit routes such as the split route 1, the split route 2, and so onexcept the initial route through the above-mentioned split processing,and selectively transmits to the reception terminal 40. The mergingsection 53 carries out selective adoption/discard processing in case ofthe identical copy, the partial copy, the flow base division processing,and so on, and carries out the reassembly (packet re-ordering)processing of packets in case of the random division, and realizes themerge processing.

(Monitor Processing on the Side of Reception Terminal)

In the switch (Egress switch) 20 at the last stage on the side of thereception terminal 40, the monitoring section 51 monitors the trafficflows before and after the merge processing by the merging section 53and notifies the monitoring result to the network control unit 30.

(Others: Branch Processing 1 of Traffic Flows of Monitoring Result)

It should be noted that when the monitoring section 51 notifies themonitoring result to the network control unit 30, the splitting section52 may split the traffic flow of the monitoring result to the networkcontrol unit 30. At this time, the network control unit 30 is equivalentto the reception terminal 40. The network control unit 30 sets a routefrom the switch 20 (the monitoring section 51) to the network controlunit 30, to the splitting section 52 based on the previous monitoringresult. For example, the monitoring section 51 transmits the trafficflow of the monitoring result to the splitting section 52 after themonitoring. The splitting section 52 splits the traffic flow of themonitoring result in the switch and the relay switch according to theplurality of split routes set by the network control unit 30. Themerging section 53 merges the split traffic flows by the switch which isthe nearest to the network control unit 30 to restore the appropriatetraffic and then transmits the merged flow to the network control unit30. That is, the monitoring result can be transmitted by use of a linkof the plurality of different switches 20-the network control unit 30.

Second Exemplary Embodiment

Next, the second exemplary embodiment of the present invention will bedescribed. In the present exemplary embodiment, as shown in FIG. 5, acase which monitoring processing is carried out by all the switches 20in the network will be described. In the present exemplary embodiment,the merging section 53 exists in the switch (Egress switch) 20 at thelast stage and the monitoring section 51 and the splitting section 52exist in optional switches 20. That is, the merging section 53 functionsonly in the switch (Egress switch) 20 at the last stage, and themonitoring section 51 and the splitting section 52 function in all theswitches in the network.

In an example of FIG. 5, the monitoring sections 51 (51-1, 51-2, 51-3)monitor the network quality of the traffic flow flowing on the initialroute from the transmission terminal 10 to the reception terminal 40 inthe relay switches 20 in addition to the switch (Egress switch) 20 atthe last stage which is the nearest the reception terminal 40. Thesplitting sections 52 (52-1, 52-2, 52-3) split the traffic flow in therelay switch. The merging section 53 merges the split traffic flows inthe switch (Egress switch) 20 at the last stage to restore anappropriate traffic flow and transmits it to the reception terminal 40.The network control unit 30 grasps the topology data of the entirenetwork, the band width data of the network link and so on, and carriesout an optimum design to a split position and a split route.

As described above, the difference from FIG. 2 is in that the conditionssuch as the packet loss in a link between the switches or congestionoccurrence can be managed, because there are the monitoring sections 51(51-1, 51-2, 51-3) in the relay switches 20. Therefore, for example, theroute which detours at the switch at the first stage is desirable whendetecting much loss by the monitoring section 51 (51-2), and the networkcontrol unit 30 adopts the split route 2 as the route for the detour bythe splitting section 52 (52-1). Or, if the performance or function isdeteriorated in the monitoring section 51 (51-3), the network controlunit 30 can determine that the route is desirable to detour one of thesplitting section 52 (52-1) and the splitting section 52 (52-2) or bothof them, because it is possible to recognize that the packet is lost onthe link between the second stage to third stage or the congestion hasoccurred. As the result of determination, the network control unit 30can determine a splitting method of a flow, a coding method, a splitposition, and a split route by the same method as in FIG. 2.

(Others: Split Processing 2 of Traffic Flows of Monitoring Result)

It should be noted that when the monitoring is carried out in all theswitches in the network like the present exemplary embodiment, thesplitting section 52 may split the traffic flow of the monitoring resultto the network control unit 30 in each switch in case that themonitoring section 51 notifies the monitoring result to the networkcontrol unit 30. At this time, the network control unit 30 is equivalentto the reception terminal 40. A route from the switch 20 (monitoringsection 51) to the network control unit 30 is set to the splittingsection 52 based on a preliminary monitoring result by the networkcontrol unit 30. For example, the monitoring section 51 transmits thetraffic flow of the monitoring result to the splitting section 52 afterthe monitoring. The splitting section 52 splits the traffic flow of themonitoring result based on the plurality of split routes which are setby the network control unit 30 in the switch and the relay switch. Themerging section 53 merges the split traffic flows in the switch which isthe nearest to the network control unit 30 and transmits the merged flowto the network control unit 30 after restoring the appropriate trafficflow. That is, the monitoring result in each switch can be transmittedby use of a link of the plurality of different switches 20-the networkcontrol unit 30.

Third Exemplary Embodiment

Next, the third exemplary embodiment of the present invention will bedescribed. In the present exemplary embodiment, a case that themonitoring and the merging are carried out in the reception terminal 40as shown in FIG. 6 will be described. In the present exemplaryembodiment, the monitoring section 51 and the merging section 53 existin the reception terminal 40 and the splitting section 52 exists inoptional switches 20. That is, the monitoring section 51 and the mergingsection 53 function only in the reception terminal 40 and the splittingsection 52 functions in all the switches in the network.

In the present exemplary embodiment, it is supposed that the receptionterminal 40 in addition to the switches 20 (20-i, i=1 to n) is providedwith the dynamic route branching unit 50.

The dynamic route branching unit 50 is provided with the monitoringsection 51, the splitting section 52, and the merging section 53.Therefore, the reception terminal 40 is provided with the monitoringsection 51, the splitting section 52, and the merging section 53, likeeach of the switches 20 (20-i, i=1 to n). However, it is not necessarythat the reception terminal 40 is provided with all of the monitoringsection 51, the splitting section 52 and the merging section 53. It issufficient that the reception terminal 40 is provided with at least oneto be used of the monitoring section 51, the splitting section 52 andthe merging section 53.

In an example of FIG. 6, the monitoring section 51A in the receptionterminal 40 monitors the network quality of the traffic flow flowing onthe initial route from the transmission terminal 10 to the receptionterminal 40. The splitting sections 52 (52-1, 52-2, 52-3) split trafficflows in the switch (Egress switch) 20 at the last stage in the networkand the relay switch. The merging section 53 merges the split trafficflows and restores an appropriate traffic to transmit it to thereception terminal 40. The network control unit 30 grasps the topologydata of the whole network, the band width data of the network link andso on and carries out the optimum design of a split position and a splitroute.

Compared with FIG. 2, the monitoring section 51 and the merging section53 are only moved from the switch (Egress switch) 20 at the last stageto the reception terminal 40. The same processing as originally executedin the switch (Egress switch) 20 at the last stage is executed in thereception terminal 40. The other processing is same as in FIG. 2.

Also, in FIG. 2, because a case that the reception terminal 40 isconnected only with a single switch (the switch at the last stage) 20 ofthe network is shown, all the traffic flows on the split route 1, thesplit route 2, and the initial route which are split in the splittingsections 52 (52-1, 52-2) are multiplexed and transmitted onto a singlelink of the switch 20 at the last stage-the reception terminal 40.

(Others: Merging of the Traffic Flows of the Monitoring Result in theNetwork Control Unit 30)

It should be noted that if the present exemplary embodiment is applied,it is possible to carry out merge processing in not the switch which isthe nearest to the network control unit 30 but the network control unit30 when the splitting sections 52 split the traffic flow of themonitoring result to the network control unit 30 in case that themonitoring section 51 notifies the monitoring result to the networkcontrol unit 30. In this case, it is supposed that the network controlunit 30 is provided with the dynamic route branching unit 50. Here, itis not necessary that the network control unit 30 is provided with allof the monitoring section 51, the splitting section 52 and the mergingsection 53, and it is sufficient that the network control unit 30 isprovided with the merging section 53 at least.

Fourth Exemplary Embodiment

Next, the fourth exemplary embodiment of the present invention will bedescribed. In the present exemplary embodiment, as shown in FIG. 7, acase in which the merging and monitoring are carried out in thereception terminal 40 in the condition that the reception terminal 40 isconnected directly with the two or more switches 20 will be described.Moreover, in the present exemplary embodiment, the reception terminal 40is connected with the two or more switches 20 at the last stage of thenetwork in the third exemplary embodiment of the present invention shownin FIG. 6.

In the present exemplary embodiment, like the third exemplaryembodiment, it is supposed that the reception terminal 40 in addition tothe switches 20 (20-i, i=1 to n) is provided with the dynamic routebranching unit 50.

Moreover, in the present exemplary embodiment, it is supposed that thereception terminal 40 is provided with a plurality of communicationinterfaces (communication ports) to communicate directly with theplurality of switches 20 (20-i, i=1 to n). The merging section 53 mergesthe traffic flows received through the plurality of differentcommunication interfaces in the reception terminal 40.

In an example of FIG. 7, the reception terminal 40 and the two switches20 (20-3, 20-4) are connected, but actually, the reception terminal 40may be connected with three or more switches 20.

In the present exemplary embodiment, each of the traffic flows of thesplit route 1, the split route 2, and the initial route split by thesplitting sections 52 (52-1, 52-2) can be transmitted by use of thelinks of the plurality of different switches 20 which-the receptionterminal 40. The network control unit 30 determines a link to be used,in consideration of the performance of the detour route.

Fifth Exemplary Embodiment

Next, the fifth exemplary embodiment of the present invention will bedescribed. In the present exemplary embodiment, a case which a wirenetwork and a wireless network are mixed will be described withreference to FIG. 8. In the present exemplary embodiment, the receptionterminal 40 is connected with the wireless network in addition to thewire network in the fourth exemplary embodiment of the present inventionshown in FIG. 7.

In an example of FIG. 8, the reception terminal 40 is connected with thewire network through one or more switches and is connected with thewireless network through one base station (BS).

Moreover, the dynamic route branching system of the present inventioncontains base stations 60 (60-k, k=1 to m: m is the number of basestations) in the present exemplary embodiment. That is, in the presentexemplary embodiment, the dynamic route branching system according tothe present invention contains the transmission terminal 10, theswitches 20 (20-i, i=1 to n), the network control unit 30, the receptionterminal 40 and the base stations 60 (60-k, k=1 to m).

Also, in the present exemplary embodiment, it is supposed that thereception terminal 40 in addition to the switches 20 (20-i, i=1 to n) isprovided with the dynamic route branching unit 50, like the third andfourth exemplary embodiments.

The base station 60 (60-k, k=1 to m) communicates directly with thereception terminal 40 as the relay unit at the last stage of thewireless network. At this time, it is supposed that the receptionterminal 40 is provided with the wire communication interfaces tocommunicate with the switches 20 (20-i, i=1 to n) and the wirelesscommunications interfaces to communicate with the base station 60 (60-k,k=1 to m).

For example, the traffic flow on the route split by the splittingsection 52 (52-1) passes through a backbone network of the wirelessnetwork and detours through one optional base station 60 (60-1). Thetraffic flow on the route split by the splitting section 52 (52-2)passes through the wire network. The merging section 53 of the receptionterminal 40 receives and merges the traffic flows on all the detourroutes. At this time, the merging section 53 merges the traffic flowsreceived through a plurality of different communication interfaces ofthe wire communication interface and the wireless communicationinterface, in the reception terminal 40. The network control unit 30determines which of the detour routes and which of links of the wirelessnetwork and the wire network should be used, in consideration of theperformance of the detour routes.

Sixth Exemplary Embodiment

Next, the sixth exemplary embodiment of the present invention will bedescribed. In the present exemplary embodiment, as shown in FIG. 9, acase where the wire network and the wireless network are mixed, and themerging and the monitoring are carried out in the reception terminal 40in the condition that the reception terminal 40 can communicate directlywith the tow or more base stations 60 will be described. Moreover, inthe present exemplary embodiment, the reception terminal 40 is connectedwith the wireless network through two or more base stations in the fifthexemplary embodiment of the present invention shown in FIG. 8.

The basic configuration of the dynamic route branching system of thepresent exemplary embodiment is same as that of the fifth exemplaryembodiment of the present invention shown in FIG. 8.

Moreover, in the present exemplary embodiment, it is supposed that thereception terminal 40 is provided with the plurality of wirelesscommunication interfaces to communicate with plurality of base stations60 (60-k, k=1 to m). In the same way, the reception terminal 40 may beprovided a plurality of wire communication interfaces to communicatedirectly with plurality of the switches 20 (20-i, i=1 to n). The mergingsection 53 merges the traffic flows received through the plurality ofdifferent communication interfaces in the reception terminal 40.

In an example of FIG. 9, the reception terminal 40 can receive thetraffic flows from two or more base stations 60 (60-1, 60-2, 60-3, 60-4)in the plurality of wireless networks at the same time. Which of detourroutes and links on the wire network and the wireless network are usedis determined by the network control unit 30 in consideration of theperformance of the detour route, like the fifth exemplary embodiment ofthe present invention.

Seventh Exemplary Embodiment

Next, the seventh exemplary embodiment of the present invention will bedescribed. In the present exemplary embodiment, as shown in FIG. 10, acase in which the merging and the monitoring are carried out in all theswitches 20 in the network and the reception terminal 40 will bedescribed. Moreover, in the present exemplary embodiment, a case inwhich the monitoring section 51 is further provided in the relay switch20 in the third exemplary embodiment of the present invention shown inFIG. 6 will be described.

In an example of FIG. 10, the monitoring sections 51 (51-1, 51-2, 51-3)are provided to monitor the network quality in the relay switch 20,compared with an example of FIG. 6. The network control unit 30 canmanage that a packet is lost in a link between which switches andcongestion has occurred, by the monitoring sections 51 (51-1, 51-2,51-3) on the relay switch 20. The split position can be selected clearerbased on these conditions.

Eighth Exemplary Embodiment

Next, the eighth exemplary embodiment of the present invention will bedescribed. In the present exemplary embodiment, a case in which thepresent invention is applied to a multicast path will be described asshown in FIG. 11.

In the other exemplary embodiments, a case in which the traffic flow offrom the transmission terminal 10 to the reception terminal 40 isunicast communication is exemplified. In an example of FIG. 11, it isassumed that the traffic flow from the transmission terminal 10 to thereception terminal 40 is the multicast communication.

In case of the multicast communication, the traffic flow isappropriately split in the switch on the way from the transmissionterminal 10 to the reception terminal 40 and is transmitted to adestination. However, when the packet loss occurs only in, for example,a specific relay link or congestion has occurred, it is not possible toapply a multipath routing control only to the link.

In an example of FIG. 11, when recognizing the function deteriorationpath in the initial route, the network control unit 30 sets to thesplitting section 52, the splitting of the traffic flow from an optionalswitch in front of the path or the splitting of the traffic flow fromany switch in the path, in order to improve the performance of the path.Here, the use of the function deterioration path continues and thetraffic flow is transmitted at both of the function deterioration pathand the detour route.

At this time, if providing the monitoring section 51 for all theswitches 20 in the network to the monitor by all the switches 20 in thenetwork, it could be considered that the function deterioration path canbe specified more correctly.

(Determination Processing of Optional Switch in Front Stage to theFunction Deterioration Path]

As a method of determining an optional switch in the front stage to thefunction deterioration path, a repetitive selecting method could bethought of in which the network control unit 30 simply selects a switchprevious to the function deterioration path, and another switch infurther front is selected when the performance of the path is notimproved even if the split route from the switch is used. Or, aselecting method could be thought of in which the network control unit30 calculates an optimal split route from the transmission terminal 10to the reception terminal in the present situation based on themonitoring result and the topology data of the whole network, and aswitch is selected to realize the optimal split route. However,actually, the present invention is not limited to these examples.

In an example of FIG. 11, the function deterioration path is only one,but actually, there sometimes are a few function deterioration paths. Insuch a case, the network control unit 30 sets appropriate execution ofthe split processing to the splitting section 52 so as to improve theperformance of each path.

By selecting and receiving the traffic flow split by the merging section53 on the side of the reception terminal 40 corresponding to themulticast communication, the traffic reception performance can beimproved.

Ninth Exemplary Embodiment

Next, the ninth exemplary embodiment of the present invention will bedescribed. In the present exemplary embodiment, as shown in FIG. 12, acase in which a final reception destination is dynamically changedthrough the splitting of the route will be described.

In the other exemplary embodiments, a case in which all of the splittraffic flows are transmitted to the switch (Egress switch) 20 at thelast stage or the reception terminal 40 has been described. On the otherhand, in the present exemplary embodiment, the traffic flow is split orbranched in an optional switch (Egress switch) 20 and is transmitted toanother unit in addition to the reception terminal 40. Here, it issupposed that another unit is a network monitoring unit 70 whichanalyzes a network situation in detail by analyzing the traffic flowitself. It should be noted that the other unit may be another receptionterminal 40.

In an example of FIG. 12, the dynamic route branching system of thepresent invention further contains the network monitoring unit 70. Thatis, the dynamic route branching system of the present invention containsthe transmission terminal 10, the switches 20 (20-i, i=1 to n), thenetwork control unit 30, the reception terminal 40 and the networkmonitoring unit 70 in the present exemplary embodiment.

The network control unit 30 sets a split route for the side of thereception terminal 40 and a split route for the side of the networkmonitoring unit 70, to the splitting section 52 on optional switch 20.It should be noted that the split route for the side of the receptionterminal 40 may be the initial route. At this time, the network controlunit 30 sets the split route for the side of the network monitoring unit70 to the splitting section 52 in the switch 20 which forms the splitroute for the side of the network monitoring unit 70.

In the relay switch 20, the splitting section 52 splits or branches thereceived traffic flow according to the route set by the network controlunit 30, and transmits the traffic flow identical to the traffic flowwhich is transmitted for the side of the reception terminal 40, to thenetwork monitoring unit 70.

Also, in the switch (Egress switch) 20 at the last stage, the mergingsection 53 merges the split traffic flows to restore an appropriatetraffic flow and transmits this traffic flow to the splitting section 52on the same the switch. The splitting section 52 splits this trafficflow according to the route set by the network control unit 30 andtransmits the traffic flow identical to the traffic flow which istransmitted for the side of the reception terminal 40, to the networkmonitoring unit 70.

In this case, the splitting section 52 transmits the traffic flowidentical to the traffic flow which is transmitted for the side of thereception terminal 40 through the identical copy, to the side of thenetwork monitoring unit 70. However, actually, a splitting method exceptthe identical copy may be adopted. For example, the splitting section 52may carry out the partial copy of only a traffic flow with a highpriority, of the traffic flows which are transmitted for the side of thereception terminal 40 and may transmit the partially copied traffic flowon the split route to the side of the network monitoring unit 70. Or,the splitting section 52 may carry out a flow base division to thetraffic flow which is transmitted for the side of the reception terminal40, and copy only the predetermined flow to transmit it on the splitroute to the side of the network monitoring unit 70.

The network monitoring unit 70 receives the traffic flow identical tothe traffic flow which is transmitted to the side of the receptionterminal 40, and analyzes this traffic flow to generate the monitoringresult which is more detailed than that by the monitoring section 51.That is, the network monitoring unit 70 can analyze in detail, thetraffic flow itself which the optional switch 20 receives. The networkcontrol unit 30 acquires the detailed monitoring result from the networkmonitoring unit 70. It should be noted that the network control unit 30and the network monitoring unit 70 may be an identical unit.

In an example of FIG. 12, the splitting section 52 splits the trafficflow on the initial route flowing through the relay switch and theswitch (Egress switch) 20 at the last stage or the traffic flow flowingthrough the split route to the network monitoring unit 70 as the trafficflow to be transmitted to the network monitoring unit 70. The networkmonitoring unit 70 analyzes the split traffic flow. Or, the mergingsection 53 merges the traffic flows split in the switch (Egress switch)20 at the last stage, and then the splitting section 52 splits therestored traffic flow in the restored condition (the condition that thequality at the reception terminal 40 can be confirmed) to the networkmonitoring unit 70 in the switch (Egress switch) 20 at the last stage orthe reception terminal 40. The network monitoring unit 70 analyzes thesplit traffic. Through the analysis, if the quality of the flow whichthe reception terminal 40 will receive is insufficient, an instructionis transmitted to the side of the network control unit 30 andoptimization is attempted by changing the algorithm.

Tenth Exemplary Embodiment

Next, the tenth exemplary embodiment of the present invention will bedescribed. In the present exemplary embodiment, a case in which thenumber of split routes is two or more in the optional switch in thenetwork will be described. In the present exemplary embodiment, thesplitting section 52 splits the traffic flow to the two or more splitroutes in the optional switch in the network.

In the other exemplary embodiments, an example of the splitting into twois shown in which a split route is generated from the initial route inthe splitting section 52. However, actually, the splitting into N (N: Nis equal to or more than 2) is possible. Also, it is possible that thesplitting section 52 splits into N routes, each of the detour routessuch as the split route 1 and the split route 2, in addition to theinitial route.

<Relation of Exemplary Embodiments>

It should be noted that the above-mentioned exemplary embodiments can becarried out by combining them. For example, the network control unit 30may set individually to carry out the split processing corresponding toeach exemplary embodiment to each of the switches 20 (20-i, i=1 to n)which are present on the plurality of different networks.

SUMMARY

As mentioned above, in the present invention, a function can be providednot to give a network a wasteful load by dynamically carrying out theoptimum design such that the cost spent to the network is minimizedthrough adoption of a multipath route.

In the dynamic route branching system of the present invention, bymonitoring the reception quality of the communication traffic on thenetwork, a split position of the traffic flow, a splitting method suchas a copy and a division, and split routes calculated to attemptoptimization based on the maximization and stabilization of thereception quality, and the traffic flow is dynamically split onto aplurality of routes by the splitting method such as copy and division inone or more optional node positions (at least one position) of the nodesthrough which the communication traffic flow passes, and the trafficflow is restored in the receiving end.

In the dynamic route branching system of the present invention, thetraffic flow quality is monitored in real time, and by a mirroringfunction (the identical copy function) which carries out the mirroringof all of the traffic flows from an optional upstream position, thewhole traffic flow is restored quickly by using the traffic flow in thesub-route, even if the phenomenon that the traffic flow is discarded inthe main route occurs due to a state change in the network, and it ispossible to improve the traffic reception performance of the receptionterminal.

Also, in the dynamic route branching system of the present invention,the traffic flow quality is monitored in real time, and by a mirroringfunction (the partial copy function) which carries out the mirroring ofonly the partial traffic flow (traffic flow with a high priority) froman optional upstream position, the traffic flow with the high priorityis restored quickly by using the traffic flow in the sub-route, even ifthe phenomenon that the traffic flow with the high priority is discardedin the main route occurs, and it is possible to improve the trafficreception performance of the reception terminal.

Also, in the dynamic route branching system of the present invention,the traffic flow quality is monitored in real time, and because there isa flow base branch function or a random branch function (a flow basedivision function, and a random division function) from an optionalupstream position, a whole band width is increased by distributing to aplurality of routes, even if the phenomenon of congestion of a networklink occurs, and it is possible to improve the traffic receptionperformance of the reception terminal.

Also, in the dynamic route branching system of the present invention,because the traffic flow quality in the reception terminal is monitoredin real time, and there is a splitting function of the traffic flow froman optional upstream position, it is possible to improve the trafficreception performance of the reception terminal, even if the phenomenonof congestion of a wireless network and a wire network occurs.

Also, in the dynamic route branching system of the present invention,because there is a function of monitoring the traffic flow quality inthe reception terminal of multicast correspondence in real time, andsplitting the traffic flow from an optional upstream position in a treeon an optional route in the multicast path, it is possible todynamically improve the traffic performance of only the route andimprove the degraded traffic reception performance of the receptionterminal of the multicast correspondence, even if the route of a part ofthe multicast path is congested so that a phenomenon that the receptionperformance of the reception terminal of the multicast correspondence isdegraded occurs.

Also, in the dynamic route branching system of the present invention,because there is a function of dynamically specifying a destination ofthe split traffic flow to a destination except the reception terminal,e.g. an address of the network monitoring unit, it is possible tooptimize an algorithm setting of the network control unit and to improvethe reception performance of the reception terminal, by dynamicallyperforming status monitoring in a necessary part in addition to theimprovement of the traffic performance of the reception terminal throughthe mirroring operation of a redundant route.

ADDITION

As described above, the exemplary embodiments of the present inventionhave been described in detail. However, actually, the present inventionis not limited to the above-mentioned exemplary embodiments and containsvarious modifications in a range which does not apart from the scope ofthe present invention.

1. A system including a plurality of nodes to forward a data packet in anetwork, the system comprising: a controller to select at least a nodedividing a data path of the data packet into a first path and a secondpath, from the nodes, based on a condition of the data path; and a nodeselected by the controller being capable of forwarding the packet to thefirst path and the second path according to an instruction from thecontroller, wherein the second path comprises a bypass path of the firstpath.
 2. The system according to claim 1, wherein the node forwards asubset of packets through the first path to the first path and thesecond path.
 3. The system according to claim 1, further comprising: amerging unit to merge packets through the first path and the secondpath.
 4. The system according to claim 1, further comprising: amonitoring unit to monitor the condition of the data path and to notifythe condition to the controller.
 5. A node to forward a data packet in anetwork, the node comprising: a first unit to receive an instructionfrom a controller which selects at least the node dividing a data pathof the data packet into a first path and a second path, from a pluralityof nodes, based on a condition of the data path; and a second unit beingcapable of forwarding the packet to the first path and the second pathaccording to the instruction, wherein the second path comprises a bypasspath of the first path.
 6. The node according to claim 5, wherein thesecond unit forwards a subset of packets through the first path to thefirst path and the second path.
 7. The node according to claim 5,further comprising: a merging unit to merge packets through the firstpath and the second path.
 8. The node according to claim 5, furthercomprising: a monitoring unit to monitor the condition of the data pathand to notify the condition to the controller.
 9. A controller tocontrol a node forwarding a packet in a network, the controllercomprising: a first unit to select at least a node dividing a data pathof the data packet into a first path and a second path, from a pluralityof nodes, based on a condition of the data path; and a second unit toinstruct dividing the data path to the node which is capable offorwarding the packet to a first path and a second path, wherein in thesecond path comprises a bypass path of the first path.
 10. Thecontroller according to claim 9, further comprising: a third unit toinstruct merging packets through the first path and the second path to anode including a merging unit to merge packets.
 11. The controlleraccording to claim 9, wherein the first unit receives the condition ofthe data path from a node including a monitoring unit to monitor thecondition.
 12. A method to forward a packet, the method comprising:receiving an instruction from a controller which selects at least thenode dividing a data path of the data packet into a first path and asecond path, from a plurality of nodes, based on a condition of the datapath; and forwarding the packet to the first path and the second pathaccording to the instruction, wherein the second path comprises a bypasspath of the first path.
 13. The method according to claim 12, furthercomprising: forwarding a subset of packets through the first path to thefirst path and the second path.
 14. The method according to claim 12,further comprising: merging packets through the first path and thesecond path.
 15. The method according to claim 12, further comprising:monitoring the condition of the data path and notifying the condition tothe controller.